Flexible abrasive coated cloth



United States Patent FLEXIBLE ABRASIVE COATED CLOTH Clayton J. Holland,Tonawanda, and Halsey W. Buell, Niagara Falls, N.Y., assignors to TheCarborundum Company, Niagara Falls, N.Y., a corporation of "Delaware NoDrawing. FiledMay 1, 1963, Sen'No. 277,093

14 Claims. (Cl. 51-,298)

This invention relates to abrasive coated cloth and is particularlyconcerned with such material which is exceptionally flexible andcharacterized by. outstanding properties in other respects.

Abrasive coated cloth is widely used in metal polishing operations andconsiderable hand polishing of metal articles isdone with abrasivecoated cloth. in many instances the abrasive coated cloth is furnishedin the form of sheets, and strips of desired width are torn from thesheets as needed.

,The invention of thepresent application has as an object the provisionof ,a novel abrasive coated cloth of improved characteristics.

A more specific object of the invention is to provide abrasive coatedcloth for metal polishing which is clean tearing.

Another object of the invention is to provide abrasive coated cloth formetal polishing which resists warping or distortion in storage.

Still another object of the invention is to provide abrasive coatedcloth for metal polishing that is unusually soft and pliable. ,1 v

A further object ofthe invention is to provide abrasive coated cloth formetal polishing in which theabrasive layer is very firmly adherenttotthe backing.

The foregoing'objects are achieved in the production of abrasive coatedcloth by the use of a making coat which comprises essentially a mixtureof animal glue, an elastomeric latex, and a plasticizer which iscompatible with both the glue and the latex. A making coat of the typedescribedpermits the production of metal-polishing abrasive cloth whichis extremely flexible, is easy to work with, and produces asuperior'finish.

The following examples illustrate the production of metal polishingabrasive cloth according to the invention. In Examples 1-5, inclusive,some of thepossible variations in the making coat are illustrated as arealso some possible changes in certain other elements and factors.

Example '1 Using a conventional coating machine of a type commonly usedin manufacturing abrasive coated paper and cloth, abrasiveparticles inthe .particle size range known as 180 grit size may be secured to amediurn-weight, finished jeans cloth with an adhesive which compriseshide glue, hexanetriol, a butadiene-styrene synthetic rubber latex, andwater. .For best results the adhesive is applied to the cloth web in anamount corresponding to about 4 /2 lbs/ream (9 in. x 11 in., 480'sheets). Such an adhesive mixture may be made from about 47 gallons ofthe latex (which comprises 48% solids), and 16 gallons of an aqueoussolution containing about 45 lbs. each of the glue and the hexanetriol.The abrasive particles are then applied over the adhesive to obtain acoated product with a grain Weight of about lbs/ream.

Example 2 Employing the same apparatus and procedure as set forth inExample 1 an abrasive coated cloth can be made by applying abrasiveparticles in the particle size range known as 150 grit size to a mediumweight, finished jeans cloth. The adhesive is applied in an amount cor-"ice responding to about 5 /2 lbs./ ream and about 12 lbs/ream ofabrasive is employed.

Examples 3-5 Employing the same apparatus and procedure as set forth inExample 1 abrasive coated cloth may be prepared with abrasive in 120,100 and grit sizes, respectively. The adhesive and abrasive are applied,respectively, in approximately the following amounts (lbs. per ream) 6,14; 6 /2, 18; and 8, 23.

It will be clear that by the same process as'set forth in the precedingexamples abrasive coatings may be applied to cloth with the abrasiveparticles in grit sizes from about 36 grit to 320 grit. The adhesivemaking coat may vary, depending on the grit size, from about 2 lbs/reamto about 20'l1bs./ream and the grain weight per ream may vary from about6 lbs. to about 65 lbs.

The adhesive of the making coats in the preceding examples is partiallyset by reducing its moisture content by conventional procedure to aboutl5%20% and an adhesive sizing coat is then applied. The followingexamples, 6 and 7, illustrate the application of such coatings. I

Example 6 The abrasive coated cloth web from Example 1 may be sized bypassing it through a conventional machine for this purpose and applyingthereto an aqueous solution of animal glue having suspended thereinfinely divided calcium carbonate. An amount of sizin-g'adhesiveequivalent to about 5 lbs/ream is preferably used, this corresponding toabout 1 /2 lbs/ream of each of the glue and filler. The final setting ofthe adhesive of the abrasive coated article may be brought about bydrying it to a final moisture content of about 6%9% by conventionalmeans.

Example 7 Abrasive coated cloth such as that made by the procedure ofExample 1 but with 80 grit abrasive grain is sized by applying theretoan aqueous sizing adhesive which deposits on the web a sizing coat thatwhen dry comprises about 2 lbs/ream of animal glue and about 4 -lbs./ream of fi-nely divided mineral filler. This sizing coat can be set bythe same procedure described in Example 6.

The sizing used in producing abrasive coated cloth in accordance withthe present invention need not contain a mineral filler, glue alonebeing usable if desired. However, the addition of a finely divided,e.g., minus 325 mesh, mineral filler in an amount constituting fromabout 50% to about 67% of the dry weight of the sizing coating is verysatisfactory. The filler used may be selected from a large number ofmineral materials. As examples, and

not in any'limiting way, there may be mentioned besidescalcium carbonate(which may be used in various forms), cryolite, silica, alumina, varioussilicates( including clays, cyanite, magnesium silicate and mullite),magnesium oxide and barium sulfate, and mixtures thereof. The exactpercentages of filler which it is preferred to use in a particularinstance will vary in accordance with the specific gravity and otherspecific properties of'the filler material. It should also be understoodthat solutions of phenolic resins, including phenol-formaldehyde resins,and urea-formaldehyde resins may be used as sizing adhesives if desired.

Abrasive coated cloth, is generally employed for polishing metal andaccordingly alumina or emery will most frequently be used as abrasivessince these are generally desired for this purpose. However, it is tob'eunderstoo'd that other abrasives may also be employed withoutdifliculty in making flexible abrasive coated cloth. 'Thus, for example,silicon carbide, garnet, and flint may be used alone or in combinationwith each other or with other abrasive materials.

In preparing the adhesive making coat the elastomeric latex used may beselected from a number of available ones. These include natural rubberlatices, butadienestyrene and butadiene-acrylonitrile copolymer latices,polychloroprene (neoprene) latices, and others having similarproperties. The plasticizer employed is preferably water-soluble andhigh-boiling with a quite low vapor pressure at ordinary temperatures.Although 1, 2, 6 hex anetriol is the most readily available one, any ofthe isomeric hexanetriols or mixtures thereof may be employed as theplasticizer. Glycerine and polyethylene glycols are further examples ofplastieizing substances that may be satisfactorily used. Hide glue ispreferred as an ingredient of both the making coat and sizing coat but agood grade of bone glue may also be used.

While the percentage of elastomer in the making adhesive on a dry weightbasis may vary from about 60% to about 80%, the range betweenapproximately 65 75% is preferred. It is preferred to use plasticizer inabout equal proportions by Weight to the dry glue but under suitableconditions the percentage of plasticizer with respect to dry glue mayvary within the range from about 75% to about 150%.

Although in the preceding examples jeans cloth has been used, it will beevident that any desired type .and weight of cloth may be employed inaccordance with known practices. The kind and weight of the cloth willof course be an important factor in determining the strength andflexibility of the product.

The product of the present invention is a very useful one and a markedimprovement over the metal polishing cloth previously available. One ofthe most important advantages of the invention is the improved adhesionof the abrasive layer tothe cloth backing. With previously producedabrasive coated metal polishing cloth it is not uncommon ot have theabrasive layer and adhesive lift from the backing. With the presentnovel product grain can be stripped from the adhesive by destructiveprocedures but the abrasive coating as a whole cannot be stripped off byhand.

It has also been found that the tearing characteristics of the novelabrasive-coated cloth of the present invention are must superior tothose of the previously produced similar product. Strips torn fromsheets have clean edgescomparable to slit edges with no fuzz, loosethread ends, or edge chipping.

Thirdly, the flexibility of the novel product is outstanding and it hasa distinctive feel or hand which is attractive to users. In addition, itis not adversely atfected by normal changes in atmospheric humidity andlies fiat in spite of such changes. a

We claim:

1. Flexible, abrasive coated cloth which comprises a cloth backinghaving a layer of abrasive granules firmly attached to one face thereofby an adhesive coating, said coating consisting of a making coat layerand a siziug coat layer, said making coat layer consisting essentiallyof a mixture of animal glue, a water-soluble, highboiling plasticizer,and an elastomer, said elastomer comprising from about 60% to about 80%of said making coat layer.

2. Anabrasive product as defined in claim 1 in which said elastomercomprises from about 65% to about 75% of said adhesive.

3. An abrasive product as defined in claim lin which the glue andplasticizer are present in about equal proportions by weight.

4. An abrasive product as defined in claim 2 in which the glue andplasticizer are present in about equal proportions by weight.

I 5. An abrasive product as defined in claim 1 in which said ela tomeris a but di eyrsne p yme t 6. An abrasive product as defined in claim 2in which said elastomer is a butadiene-styrene copolymer.

7. An abrasive product as defined in claim 1 in which said plasticizeris hexanetriol.

8. An abrasive product as defined in claim.2 in which said plasticizeris hexanetriol.

9. An abrasive product as defined in claim 1 in which said plasticizeris hexanetriol and said elastomer is a butadiene-styrene copolymer andin which said elastomer comprises from about 65% to about of saidadhesive and said glue and said plasticizer are present in about equalproportions by weight.

10. A process for producing a flexible, abrasive-coated cloth whichcomprises applying to a cloth backing a coating of an aqueous adhesivewhich consists essentially of water containing a mixture of animal glue,a watersoluble, high-boiling plasticizer, and an elastomeric latex insufiicient amount to constitute from about 60% to about of the dryweight of said adhesive, applying to said coating before drying a layerof abrasive granules, setting said adhesive by partially drying it, andapplying an adhesive size coat over said layer of abrasive granules.

11. A process for producing a-flexible, abrasive-coated cloth whichcomprises applying to a cloth backing a coating of an aqueous adhesivewhich consists essentially of Water containing a mixture of animal glue,a watersoluble, high-boiling plasticimr, and an elastomeric latex insufiicient amount to constitute from about 65 to about 75 of the dryweight of said adhesive, applying to said coating before drying a layerof abrasive granules, setting said adhesive by partially drying it, andapplying an adhesive size coat over said layer of abrasive granules.

12. A process for producing a flexible, abrasive-coated cloth whichcomprises applying to a cloth backing a coating of an aqueous adhesivewhich consists essentially of water containing a mixture of animal glue,a watersoluble, high boiling plasticizer, said glue and latex beingpresent in about equal proportions by weight, and an elastomeric latexin sufficient amount to constitute from about 60% to about 80% of thedry weight of said adhesive, applying to said coating before drying alayer of abrasivegranules, setting said adhesive by partially drying it,and applying an adhesive size coat over said layer of abrasive granules.

13. .An abrasive product as "defined in claim 1 in which saidplasticizer is hexanetriol and said elastomer is produced from a latexselected from the group consisting of natural rubber latices,butadiene-styrene latices, butadiene acrylonitrile latices, andpolychloroprene latices and in which said elastomer comprises from about65 to about 75 of said adhesive and said glue and said plasticizer arepresent in about equal proportions by weight.

14. An abrasive product as defined in claim 1 in which said sizing coatincludes a finely divided filler.

References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCESCondensed Chemical page 572.

ALEXANDER H. BRODMERKEL, Primary Examiner, MORRIS 'Ll BMAN, Examiner.

Dictionary, Sixth edition, 1961,

1. FLEXIBLE, ABRASIVE COATED CLOTH WHICH COMPRISES A CLOTH BACKINGHAVING A LAYER OF ABRASIVE GRANULES FIRMLY ATTACHED TO ONE FACE THEREOFBY AN ADHESIVE COATING, SAID COATING CONSISTING OF A MAKING COAT LAYERAND A SIZING COAT LAYER, SAID MAKING COAT LAYER CONSISTING ESSENTIALLYOF A MIXTURE OF ANIMAL GLUE, A WATER-SOLUBLE, HIGHBOILING PLASTICIZER,AND AN ELASTOMER, SAID ELASTOMER COMPRISING FROM ABOUT 60% TO ABOUT 80%OF SAID MAKING COAT LAYER.